A nail bomb exploded outside a pub in Macau early yesterday, destroying six cars, extensively damaging four pubs and karaoke bars and shattering all the windows in a five-storey building. Police suspect the bombing, outside the Bistro Pub in Rua Formosa at 3.40am, was a revenge attack over a business dispute. No one was hurt in the blast. Police later questioned a man after witnesses gave them the licence plate number of a car seen speeding from the scene seconds after the explosion. The blast was the most powerful in a series of bombings that have rocked the Portuguese enclave since the beginning of this year. Ten people have been injured in the 13 attacks.